Sub-band speech coding system
First Claim
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1. A wide band signal coder comprising:
- means for subdividing signals over a bandwidth into a lower subband and a higher subband signals, a downsampler for downsampling said lower subband signals, a low band speech coder coupled to said downsampler for encoding said downsampled lower subband signals, and a highband coder for coding said higher subband signal without downsampling, and a combiner for combining said higher and lower subband signals.
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Abstract
An improved sub-band speech coding system is provided by subdividing signals into a lower an higher subband, downsampling the lower subband before coding and coding the higher subband without downsampling. The decoder includes decoding and upsampling of the lower subband and decoding the higher subband and adding the higher subband to the lower subband.
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Citations
20 Claims
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1. A wide band signal coder comprising:
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means for subdividing signals over a bandwidth into a lower subband and a higher subband signals, a downsampler for downsampling said lower subband signals, a low band speech coder coupled to said downsampler for encoding said downsampled lower subband signals, and a highband coder for coding said higher subband signal without downsampling, and a combiner for combining said higher and lower subband signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A speech coding system comprising:
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means for subdividing signals over a bandwidth into a lower subband and a higher subband, a downsampler for downsampling said lower subband signals, a low band speech coder coupled to said downsampler for encoding said downsampled lower subband signals, a highband coder for coding said higher subband signal without downsampling;
a bandpass filter coupled to said highband coder to bandpass said higher subband signal to complement the lower subband;
a first decoder for decoding said encoded lower subband signals;
means for upsampling and lowpass filtering said lower subband signals to the same rate as the higher band signals;
a second decoder for decoding said higher subband signals and bandpass filtering said higher subband signals; and
and adder for summing said lower subband signals and said higher subband signals - View Dependent Claims (11, 12, 13, 14, 15, 17, 18, 19, 20)
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16. A wideband speech decoder system comprising:
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a first decoder for decoding encoded lower subband signals;
a second highband decoder for decoding higher subband signals at a higher sampling rate than said lower subband signals;
a converter for converting said lower subband signals to the same sampling rate as the higher band signals; and
an adder for summing said lower subband signals and said higher subband signals.
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Specification